At present, the Imaging Core of the Center for Cardiovascular Research houses one Olympus laser scanning confocal microscope (Fluoview FV300) equipped with Krypton, Argon and He/Ne lasers for confocal microscopy and Mercury and Halogen lamps for epifluorescence and DIC/phase contrast/bright field microscopy, respectively. The confocal unit is mounted on an inverted Olympus microscope (1X70) with a universal high NA condenser. For capturing non-confocal images, a Spot CCD camera is used. This confocal microscope will be used for the proposed PPG projects. There is an up-right Olympus microscope (BX51) for epifluorescence, phase contrast, and DIC observations. The scope is also equipped with a Spot CCD camera. This scope is used for routine immunofluorescence observations, especially for en face analyses of immunostained endothelial tissue. Specimens for immunofluorescence microscopy are prepared by individual investigators. Technical suggestions and advice are given to them, such as fixation and staining conditions, blocking, and mounting. Data acquisition is done with the help of the Core Director and an assistant using a TV monitor. Those who wish to use the scopes by themselves are given instructions by the Core Director. MCID Elite 6.0 (Imaging Research Inc.) is available for the studies proposed in this application. The software is capable of performing various forms of image analyses such as image enhancement, image processing and editing, and 3D reconstruction. It has also functions that are quantitative such as profiling (vertical, horizontal, rotatable, and user-traced lane definition), stereology for unbiased morphological measurements and quantification, and grain counting. The grain counting mode is applicable to cells, grains, organelles, and other discrete objects. Valid targets are discriminated from background based on their intensity, color and spatial criteria.